If your want to insert a piece of code, you will have to renumber all your lines. Sure, you might number with increments of 10, but then, what if you want to insert 11 lines of code? Or first you insert 10 lines, then later on, between that, another 10?

Also, what are you going to do with statements that are longer than a line? Can you just arbitrary put numbers in those statements? It gets worse with strings that span multiple lines. Do they need to be numbered?

The bottom line is, there is absolutely no reason to number the lines of your code. If you find it handy to have line numbers while coding, use power editor like vi that will allow you to view line numbers.

Note that you can use line numbers in Perl. Or at least, sort of:

L0: print "Begin of program.\n";
L1: print "Hello, world.\n";
L2: ;# Some comment.
L3: print "End of program.\n";
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Begin of program.
Hello, world.
End of program.

Abigail

Well, that settles that. I wasn't necessarily planning on programming by numbers, but I wanted to gather thoughts on doing so. Fortunately, I've been working for a long time without line numbers, so I'll be just fine there.

As for a language that should be used for beginning programmers...as said above, BASIC isn't bad, but it isn't good, either. Perhaps Java would be a good way to start out. The school I attended has since dropped BASIC and gone to C, which I think is a mistake (due to complexity).

You never know what you'll learn from asking a question like this :)

In fact, they're even more limited than you'd think in perl, since in some cases, the error message points to the wrong line.

But they're still a very good way to know where the bug was, as long as you still have the exact version of the script that was running by the time you see the error in your logs. (That's one of the reasons version control is so important...)

For more useful, but more verbose error messages, you might want to use the cluck and confess calls from the Carp module. They give you a full backtrace for where you warned/died, which might be more robust than just the line number...
--
Mike

()-()
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  `                                                     

Should we start them on C++ or Java instead? Don't laugh, I've seen it done! As wrong as BASIC is I think it makes a pretty good starter language. Can you suggest any reasonable alternatives?

-sam

A reasonable alternative for BASIC? No, I don't think there is. Nor do I think BASIC is reasonable. But I do think there are good candidates for good starter languages: Python, Modula, Haskell, Java, and probably Eifel as well. Not BASIC, not C, not C++ and certainly not Perl.

Abigail

As others have said, line numbering is quite annoying if you need to reorder or refactor your code, since changing them (and only them) is probably necessary. In fact, I'm now having flashbacks to programming my C-64. Thanks a lot! ;)

I would hope that explicit (label) line numbers are passé. That said, I generally edit with line numbers displayed (set nu in vi and friends); it makes moving quickly around the screen very easy, and gives you another, very visible indication of how long your (block|function|code) is getting.

--
The hell with paco, vote for Erudil!
:wq

Of course, you can always reindex and (label) your line numbers using the line pragma. For instance:

#!perl -w
use strict;

# after the next line, error messages will be indexed 
# starting at line 300 and contain the phrase "marked_point"

#line 300 marked_point
my $some_var;
$some_var = "some_value";
blah;
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Which yields:

Bareword "blah" not allowed while "strict subs" in use at marked_point
+ line 302.
[download]

This is pretty handy from a debugging standpoint during development. For instance, you could give each major block of code its own series; such as, main code gets lines 0-999, and each subroutine gets a 1000 line block and a label. So if you got an error message like:

Missing right curly or square bracket at subroutine_save_report line 3
+010, at end of line
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You'd know exactly where to look. Best to take them out line labeling when code goes production, however...

While you do make valid arguments in favour of line numbers, none of them mandate that the line numbers be in the file. A good editor alone will address your needs.

Take vi: :set number shows line numbers, and either :10 or 10G will take you to the 10th line of the file. Any other decent editor will offer equivalents.

Makeshifts last the longest.